Wallboard



Dec. 7, 1943. G.\A. HOGGATT.

WALL BOARD Filed Jan. 4, 1940 Vwallboards; of this type. 1

Patentedrec. 7,

A' UNITED 4s'mfias PATENT.. narici?.A

come a. noma. Snyder, N. Y.. minor a L assessment-arcta am Accusation .mmm 4, 1era-semina. :lasst l s claims. -(ci. a-45.9)

This invention relates to wallboards or panels, especially those having a core of hydraulic-setting cementitious material. yThe invention particularly relates to gypsum wallboards in which a core of calcined gypsum in set condition lies between cover papers adhering thereto.

Wallboards and panels having a core of hymade in-'many forms. A common form is that made of calcined gypsum which has been pre-l pared as a mortar orslurry and placed between cover sheets of paper of suitable strength, thick ness and other characteristics which cause the paper to .adhere to the core whenv set and fo provide a facing for said core. An important funcdraulic-setting cementitious material have been tion of said cover papers isthat, being located at the faces of the core. they are able to take the stress applied to the wallboard which causes tension at these faces. The core itself, particularly with gypsum wallboards, is usually frangible. The cover papersai'ford the necessary rec sistance about a neutral axis within the core thus to resist deformation and breakage of the panel. The strength thus given to the panel is considerable -so that wallboards of this type are c used to span across the spaces betweenl studs and ceilingV beams when fastened thereto by or- 4dinary fasteners such as nails. These fasteners are driven through the cover papers and the core to enter the studs or beams. 'I'he cover papers likewise serve as a reinforcement around the core at the point-s where the nails are driven therethrough.

The cover papers upon the frangible core, however, have a certain resilience and stretch. They are not capable of resisting compressive strains. The core material alone, particularly of calcined gypsum. is not capable of resisting without frac- `titre any substantial deformation under forces to avoid breakage and to avoid damage caused by crushing of the core. l f. I f Y It is an object of the invention to provide a wallboard having such a core of hydraulic-setting material which is more rigid thanthe usual Itis a further obiect of A vide a wallboard havinganA hydraulic-setting core, particularly one with a core of calcined gypsum, which will have greater resistance to crushing under a blow upon the face of the panel c and .un'der stress which may be brought upon the panel after erection because of the expans ion and contraction and settlement and otherV Causes'.

A particular object of the invention 'is yto prov vide a core of suchconstruction that it will c0- operate with the4 coverpapers tb provide greater rigidity and strength in the panel and greater re-` sistance to damage without substantial increase in the weight of the materials usually used and without substantial increase in the finished weight of the panel. Y l

The drawing illustrates a portion of a wall- Aboard embodying the invention. l l It has been proposed heretofore to provide in l the core of a'gypsum wallboard a portion at its center which is of less vdensity than a layer of gypsum which is next to the cover. paper. ByA

maintaining adjacent the cover paper a layer of the gypsum of the usual composition while mak--V ing the inner portion oflight weight a wallboard of lighter weight but of no greaterstrength than 'finished panel is ordinary wallboard was secured.

In the present inventionthe core material is made in any known manner and may be of iight weight as proposed in the prior art or of ordinary density and strength as in common practice. Such core materials when made with calcined gypsum. for example, ordinarily have theI characteristic that to secure a pouring consistency in the slurry to b e applied between the cover papers to `80 parts of water for each- 100 parts of thedry cementitious materialare required. Such is more orless porous, that is not dense, because .Y i Y of the voids which arelei't upon evaporation of the water. When, as has been suggested in the pri'orart, gas or bubble ,forming materials are incorporated to increase the porosity of the hy.

draulic-setting material a core of still less densitylis secured. In all such cores. however, this de crease in density and, therefore, lweight of the obtained at the expense of.

strength. 1 v

Invthe productof the present invention the inner portion of the core may be made of any suitable composition but between said core and one or both cover papers is placed a layer or layers of:an hydraulic-setting material of auch the invention to prostantially less than-'15%.

in said layers as compared with core materials which have been used heretofore. In order to secure this greater density, hydraulic-setting materials having inherent characteristics as to the crystalline structure thereof may be used; also those which are of such composition as to reing consistency are used. Hydraulic-setting maquire little water to securethe necessary pourterials of either type for pouring consistency may require water to the extent only oi 30 to 50 parts of water for each one hundred parts of the hydraulic-setting material inthe dry state byA weight.

A material in which the low water-carrying capacity for pouring consistency isobtained by virtue of its crystalline structure is disclosed in the patent to Wilbur S. Randel and Manvel C. Dailey, No.` 1,901,051, oi Marchy 14, 1933. In said patent is described a process of'calcining gypsum rock under controlled conditions of pressure, time y been proposed for the interposed layer are capa'-l and temperature which insure high tensile and compressive strengths in the casts made irom the calcined gypsum. The patent describes the product as a new type ofcalcium sulphate hemihydrate which is substantially entirely monomineralic and consists solely of crystal fragments consisting of pure calcium sulphate hemihydrate requiring a great deal less water to convert them into a cementitious slurry of normal pouring consistency as compared'with the' prior art products.

preferably-while both the core material and the A material having the requisite properties by.

virtue of its composition is .disclosed in' the patent to Harry F. Gardner, No. 1,996,372 of April 2. 1935. In this latter patent the low water-carrying capacity is obtained by the admixture with calcined gypsum of a saccharide. such as gum arabic, and an alkaline material, such. as lime.

The alkaline materials disclosed in the patent in general are the alkalies, including ammonia, the alkaline carbonates and borates, as well as the organic alkali hexamethylenamine. In some formulae of the Gardner patent a lead compound. such as litharge,l may be included, particularly when litharge and soda ash arel used together with gum arabic in the composition. In the patent also the advantage o! using calcinedgypsum v which has been tube milled is explained. The

.patent alsodiscloses certain speciilcoomposbtions to secure optimum results in such a high density hydraulic-setting material. Examples of such compositions as are proposed by the patent are given therein and ranges of the percent of the effective ingredients of `the composition. Thus the amount of the saccharide, such as gum arabic, may vary from .4% to 10% and of the alkaline material from .01% tov 2%. The amount Y vWithin the scope of the invention, however, any hydraulic-setting material, particularly any calcined gypsum, which has 'been prepared so as. to have the property of not requiring substantially in excess o! 45 parts of water i'or each 100 parts of the dry material in order to secure pouring consistency may be used.` Instead of or in addition to the gum arabic oi the composition ci the Gardner Patent No. 1,996,372, other vegebe used to improve' the bond of the cover pape .to the interposed dense layer.

In the drawing the coreot the wallboard of ordinary density and strength is shown at 3. Between said core and the cover papers 1 at each face of the wallboard the layer 6 is interposed.

-These layers according to the invention are formed'of the hydraulic setting material of low water carrying capacity and may be provided by calcined gypsum of the type described in said patent to Randel and Dailey or of the type described in said patent to Gardner.

When such an hydraulic-setting material is used as the layer intervening or lying between the usual core material and the cover papers the desired results of rigidity, strength, resistance to crushing and ari-improved backing for the cover -paper are secured. The materials which have ble, as with the ordinary core materials, of aiord- 'ing the necessary bond of the cover papers to the core material, that is, to the layer. The materials for the layer also are capable oi setting either in contact' with the dry set core material or material of the interposed layers are in the process of setting to securethe necessary bond between the layers and the corematerial. Thus.

adjacent'the surface of the core the invention provides a stiiiening element capable oi' resisting greater stress of compression applied thereto and in many cases greater stress of tension. Strains tending to cause deformation and breakage are thus resisted. This element. that is. the layer capable of taking increased compression, acts with the tension member in the form of the cover paper so that strains resulting from stresses l'of tension or compression are satisfactorily resisted.

Having thus described my invention I now l claim:

1. A composition wallboard comprising a cove'r sheet of brous structure, a base core of hydraulic setting cementitious material in set condition, and a; layer of hydraulic setting cementitious material in set condition requiring for pouring consistency not substantially greater than parts of water .to 100 parts'of said material in dryl condition and securing in said set layer a greater density and strength than that of the base core, said layer f lying between and adheringto said cover sheet and tosaid base core.

2. A gypsum wallboard comprising a paper cover4 sheet, a base core in set condition of calcined gypsum requiring for pouring consistency l rnot 'substantially less than 60 parts of water to 100 parts of the dry calcined gypsum, and a layer in set condition of hydraulic setting ma-I terial comprising calcined gypsuml and requiring for pouring. consistency not substantially greater than 50 parts of water to 100 parts of the dry hydraulic setting material, said layer in set con- .dition lying between and adhering to saidvpaper cover sheet and to said base core.

3. A' gypsum wallboard comprising a paper" table materials which will act as adhesives may and the alkaline borates, the amount of the alkw paper cover'sheet and said luasecore.`

4. A gypsum waliboard comprising a paper cover sheet, a base core in set condition of calcined gypsum requiring for pouring consistency not substantially less than 60 parts of water to 100 parts of the dry calcined gysum, and a layer in set condition o! hydraulic setting material comprising calcined gypsum in amount not substantially less than '75%, a' saccharide, a lead compound, and an alkaline material, the amount of the alkaline material being not substantially greater than that of the saccharide, said percentage being based on the sum of the weights of said four ingredients of said layer as a dry mixture, said layer in set condition lying between and adhereing to said paper cover" sheet and to said base core.

5.. A gypsum waliboard comprising a paper cover sheet, a'base core in set condition of calcined gypsum requiring forpouring consistency not substantially less than 60 parts of water to 100 parts of the dry calcined gypsum, and a layer" in set condition o! hydraulic setting material comprising calcinedgypsum, gum arabic, and an alkaline material, the percentage of calcined 100 parts of the dry calcined gypsum, and -a layer in set condition of hydraulic setting material comprising calcined gypsum in amount not sub- -1 stantially less than 75%, gum arabic in amount between .4% and 10%, an alkaline material vin amount between '.01% and 2%, said lPercentagesl being basedsonvthe sum of the weights o f said three ingredients as a dry mixture, said layer` lying between and adhering to said paper cover sheet and to said lbase core.

7. A gypsum wallboard comprising a paper cover sheet. a base core in set condition of calcined gypsum requiring for pouring consistency not substantially less than 60 parts of water to 100 parts of the dry calcined gypsum, and a layer in set condition of hydraulic setting material comprising calcined gypsum in amount not substantially less than 75%. gum arabic-in amount 1` between .5% and 10%, litharge in amount becentages being based on the sum of the amounts gypsum inI said layer being not substantially less than 75% based on the sum of the weights of said three ingredients oi. said layer as a dry mixture,-

the 'percentage oi the gum arabic being not subf stantially less .than that of the` alkaline material, said layer in set condition lying between and adhering to saltiV paper cover sheet and to by weight of said four ingredients oi said layer as a dry mixture, said layer in set condition lying between and adhering'to said paper cover sheet and to said base core.

8. A gypsum wallboard comprising a paper cover sheet, a base core in set condition of caly cined gypsum requiring for pouring consistency not substantially less than parts of water to parts of the dry calcined gypsum, and a layer in set condition f hydraulic setting material comprising substantially pure crystalline `finely ground calcium sulphate hemihydrate requiring to produce pouring consistency the addition of not substantially more than 50 parts of.

GILBERT HOGGATI. v 

